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Net Energy Value of Ethanol Increases, Says USDA

National Corn Growers Association | Jun 10, 2004

Preliminary findings of a new study on the net energy balance of ethanol indicate ethanol produces 67% more energy than it takes to generate. The study, “The 2001 Net Energy Balance of Corn-Ethanol,” was presented at the Corn Utilization and Technology Conference (CUTC) by Hosein Shapouri, a USDA economist.

Shapouri said his research proves ethanol undoubtedly has a positive energy balance, even before subtracting the energy allocated to coproducts. In a 1996 study, Shapouri calculated the net energy balance of ethanol at 36%, up from 24% in 1991. Technological advances in crop production and the ethanol plant have helped to reduce the amount of energy required to produce ethanol, he said.

“Corn yields per acre have increased, fertilizer is more energy efficient and ethanol plants are more efficient,” Shapouri said. “So the net energy value of corn-ethanol improves.”

According to Shapouri’s research, the wet-milling process produces a net energy value of 57%, while dry-milled ethanol produces 77% more energy than it takes to produce.

Shapouri’s research discredits the work of Dr. David Pimentel, who in 2003 mistakenly concluded that ethanol takes more energy to produce than it generates. “This (research), unlike the Dr. Pimentel report in 2003, is based on straightforward methodology and highly regarded quality data,” Shapouri said. Numerous economists have questioned the validity of Pimentel’s findings, arguing that he uses outdated data in his methodology.

Shapouri said one objective of the study was to improve the quality of data and estimation methodology used in past studies. For the newest study, USDA exhaustively surveyed corn farmers and ethanol plants and used new process simulation programs to allocate energy.

“Our data is crystal clear,” Shapouri said. “We used a USDA corn survey and we also used a survey of ethanol plants, so you can see the data from the first step of the process all the way until ethanol goes into the tank of your car.”

And as technology continues to improve, so will the energy value of ethanol, Shapouri says. Higher yields, more energy efficient inputs and improved technologies in ethanol plants will drive the energy balance of ethanol even higher, he said.

“We believe the net energy balance is going to increase because of technology in corn production and technology in ethanol,” he said. “The research proves this.”